A large amount of solder oxides are formed when electronic parts are soldered on the printed wiring board using a dip-type soldering apparatus or a flow-type soldering apparatus. Moreover, when the solder oxides are scooped up from molten solder or drained from a solder bath to solidify, a large amount of solder is observed to be adhered to the solder oxides.
The solder oxides with solder adhered thereto are sold to the regenerators at a low price. In order to prevent oxidation of solder, an anti-oxidizing agent such as heat-resistant mineral oil has been added to the surface of molten solder, or a solder bath and its surroundings have been enclosed with an inert gas such as nitrogen gas so that the oxygen concentration is reduced to minimize oxidation of solder.
On the other hand, a powdery product obtained by adding a potassium salt to ammonium borohydrochloride is commercially available as a separating/reducing agent for solder oxides, which can separate solder from solder oxides with solder adhered thereto to remove only solder oxides (tradename/KLEENOX OR-904P/sold by ELECTROVERT).
In addition, for example, JP-A-5-63349 and the like proposed a wave solder bath equipped with a means for flowing solder oxides from the solder bath together with a heat-resistant fat and oil.
However, the previous selling of the solder oxides to the regenerators has a great loss of solder because a large amount of expensive solder is adhered to solder oxides.
The addition of the anti-oxidizing agent to the surface of molten solder makes the solder bath stickily smeary with the anti-oxidizing oil and the like, which leads to not only troublesome cleaning but also adherence to the printed wiring board and the like.
The solder bath disclosed in JP-A-5-63349 also has a similar problem in that the heat-resistant fat and oil is accumulated in a solder reservoir, or a duct for solder is clogged with the fat and oil.
The use of the inert gas results in a higher cost and requires larger and more complicated facilities.
The powdery separating agent containing ammonium borohydrochloride as a main component is expensive at about 6,000 yen/450 g and, upon handling, requires safety management such as paying attention so as not to make the agent touch the skin, wearing eyeglasses for protecting eyes, and the like.